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arm64: Support overflow stack panic
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Overflow stack supported since kernel 4.14 in commit 872d8327ce8,
without this patch, bt command trigger a SIGSEGV fault due the SP
pointed to the overflow stack which not yet loaded by crash.

Before:

      KERNEL: ../vmlinux
    DUMPFILE: la_guestdump.gcore
        CPUS: 8
        DATE: Tue Jul 13 19:59:44 CST 2021
      UPTIME: 00:00:42
LOAD AVERAGE: 3.99, 1.13, 0.39
       TASKS: 1925
    NODENAME: localhost
     RELEASE: 4.14.156+
     VERSION: crash-utility#1 SMP PREEMPT Tue Jul 13 10:37:23 UTC 2021
     MACHINE: aarch64  (unknown Mhz)
      MEMORY: 8.7 GB
       PANIC: "Kernel panic - not syncing: kernel stack overflow"
         PID: 1969
     COMMAND: "irq/139-0-0024"
        TASK: ffffffcc1a230000  [THREAD_INFO: ffffffcc1a230000]
         CPU: 0
       STATE: TASK_RUNNING (PANIC)

crash-7.3.0> bt
PID: 1969   TASK: ffffffcc1a230000  CPU: 0   COMMAND: "irq/139-0-0024"
Segmentation fault (core dumped)

After:

crash> bt
PID: 1969   TASK: ffffffcc1a230000  CPU: 0   COMMAND: "irq/139-0-0024"
  #0 [ffffffcc7fd5cf50] __delay at ffffff8008c80774
  crash-utility#1 [ffffffcc7fd5cf60] __const_udelay at ffffff8008c80864
  crash-utility#2 [ffffffcc7fd5cf80] msm_trigger_wdog_bite at ffffff80084e9430
  crash-utility#3 [ffffffcc7fd5cfa0] do_vm_restart at ffffff80087bc974
  crash-utility#4 [ffffffcc7fd5cfc0] machine_restart at ffffff80080856fc
  crash-utility#5 [ffffffcc7fd5cfd0] emergency_restart at ffffff80080d49bc
  crash-utility#6 [ffffffcc7fd5d140] panic at ffffff80080af4c0
  crash-utility#7 [ffffffcc7fd5d150] nmi_panic at ffffff80080af150
  crash-utility#8 [ffffffcc7fd5d190] handle_bad_stack at ffffff800808b0b8
  crash-utility#9 [ffffffcc7fd5d2d0] __bad_stack at ffffff800808285c
--- <IRQ stack> ---
 crash-utility#10 [ffffff801187bc60] el1_error_invalid at ffffff8008082e7c
 crash-utility#11 [ffffff801187bcc0] cyttsp6_mt_attention at ffffff8000e8498c [cyttsp6]
 crash-utility#12 [ffffff801187bd20] call_atten_cb at ffffff8000e82030 [cyttsp6]
 crash-utility#13 [ffffff801187bdc0] cyttsp6_irq at ffffff8000e81e34 [cyttsp6]
 crash-utility#14 [ffffff801187bdf0] irq_thread_fn at ffffff8008128dd8
 crash-utility#15 [ffffff801187be50] irq_thread at ffffff8008128ca4
 crash-utility#16 [ffffff801187beb0] kthread at ffffff80080d2fc4
crash>

Signed-off-by: Hong YANG <[email protected]>
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@yangh
yangh committed Nov 15, 2021
1 parent 8246dce commit 881fda8
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Showing 2 changed files with 93 additions and 4 deletions.
91 changes: 87 additions & 4 deletions arm64.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,7 @@ static int arm64_vtop_3level_4k(ulong, ulong, physaddr_t *, int);
static int arm64_vtop_4level_4k(ulong, ulong, physaddr_t *, int);
static ulong arm64_get_task_pgd(ulong);
static void arm64_irq_stack_init(void);
static void arm64_overflow_stack_init(void);
static void arm64_stackframe_init(void);
static int arm64_eframe_search(struct bt_info *);
static int arm64_is_kernel_exception_frame(struct bt_info *, ulong);
Expand Down Expand Up @@ -78,8 +79,11 @@ static int arm64_get_smp_cpus(void);
static void arm64_clear_machdep_cache(void);
static int arm64_on_process_stack(struct bt_info *, ulong);
static int arm64_in_alternate_stack(int, ulong);
static int arm64_in_alternate_stackv(int cpu, ulong stkptr, ulong *stacks, ulong stack_size);
static int arm64_on_irq_stack(int, ulong);
static int arm64_on_overflow_stack(int, ulong);
static void arm64_set_irq_stack(struct bt_info *);
static void arm64_set_overflow_stack(struct bt_info *);
static void arm64_set_process_stack(struct bt_info *);
static int arm64_get_kvaddr_ranges(struct vaddr_range *);
static void arm64_get_crash_notes(void);
Expand Down Expand Up @@ -463,6 +467,7 @@ arm64_init(int when)
machdep->hz = 100;

arm64_irq_stack_init();
arm64_overflow_stack_init();
arm64_stackframe_init();
break;

Expand Down Expand Up @@ -1715,6 +1720,50 @@ arm64_irq_stack_init(void)
}
}

/*
* Gather Overflow stack values.
*
* Overflow stack supported since 4.14, in commit 872d8327c
*/
static void
arm64_overflow_stack_init(void)
{
int i;
struct syment *sp;
struct gnu_request request, *req;
struct machine_specific *ms = machdep->machspec;
ulong p, sz;
req = &request;

if (symbol_exists("overflow_stack") &&
(sp = per_cpu_symbol_search("overflow_stack")) &&
get_symbol_type("overflow_stack", NULL, req)) {
if (CRASHDEBUG(1)) {
fprintf(fp, "overflow_stack: \n");
fprintf(fp, " type: %x, %s\n",
(int)req->typecode,
(req->typecode == TYPE_CODE_PTR) ?
"TYPE_CODE_PTR" : "other");
fprintf(fp, " target_typecode: %x, %s\n",
(int)req->target_typecode,
req->target_typecode == TYPE_CODE_INT ?
"TYPE_CODE_INT" : "other");
fprintf(fp, " target_length: %ld\n",
req->target_length);
fprintf(fp, " length: %ld\n", req->length);
}

if (!(ms->overflow_stacks = (ulong *)malloc((size_t)(kt->cpus * sizeof(ulong)))))
error(FATAL, "cannot malloc overflow_stack addresses\n");

ms->overflow_stack_size = ARM64_OVERFLOW_STACK_SIZE;
machdep->flags |= OVERFLOW_STACKS;

for (i = 0; i < kt->cpus; i++)
ms->irq_stacks[i] = kt->__per_cpu_offset[i] + sp->value;
}
}

/*
* Gather and verify all of the backtrace requirements.
*/
Expand Down Expand Up @@ -2673,6 +2722,12 @@ arm64_back_trace_cmd(struct bt_info *bt)
bt->hp->eip : GET_STACK_ULONG(bt->hp->esp);
stackframe.sp = bt->hp->esp + 8;
bt->flags &= ~BT_REGS_NOT_FOUND;
} else if (arm64_on_overflow_stack(bt->tc->processor, bt->frameptr)) {
arm64_set_overflow_stack(bt);
bt->flags |= BT_OVERFLOW_STACK;
stackframe.sp = bt->stkptr;
stackframe.pc = bt->instptr;
stackframe.fp = bt->frameptr;
} else {
if (arm64_on_irq_stack(bt->tc->processor, bt->frameptr)) {
arm64_set_irq_stack(bt);
Expand Down Expand Up @@ -3881,20 +3936,38 @@ arm64_on_irq_stack(int cpu, ulong stkptr)
}

static int
arm64_in_alternate_stack(int cpu, ulong stkptr)
arm64_in_alternate_stackv(int cpu, ulong stkptr, ulong *stacks, ulong stack_size)
{
struct machine_specific *ms = machdep->machspec;

if (!ms->irq_stack_size || (cpu >= kt->cpus))
if (!stack_size || (cpu >= kt->cpus))
return FALSE;

if ((stkptr >= ms->irq_stacks[cpu]) &&
(stkptr < (ms->irq_stacks[cpu] + ms->irq_stack_size)))
if ((stkptr >= stacks[cpu]) &&
(stkptr < (stacks[cpu] + stack_size)))
return TRUE;

return FALSE;
}

static int
arm64_in_alternate_stack(int cpu, ulong stkptr)
{
struct machine_specific *ms = machdep->machspec;

return arm64_in_alternate_stackv(cpu, stkptr,
ms->irq_stacks, ms->irq_stack_size);
}

static int
arm64_on_overflow_stack(int cpu, ulong stkptr)
{
struct machine_specific *ms = machdep->machspec;

return arm64_in_alternate_stackv(cpu, stkptr,
ms->overflow_stacks, ms->overflow_stack_size);
}

static void
arm64_set_irq_stack(struct bt_info *bt)
{
Expand All @@ -3905,6 +3978,16 @@ arm64_set_irq_stack(struct bt_info *bt)
alter_stackbuf(bt);
}

static void
arm64_set_overflow_stack(struct bt_info *bt)
{
struct machine_specific *ms = machdep->machspec;

bt->stackbase = ms->overflow_stacks[bt->tc->processor];
bt->stacktop = bt->stackbase + ms->overflow_stack_size;
alter_stackbuf(bt);
}

static void
arm64_set_process_stack(struct bt_info *bt)
{
Expand Down
6 changes: 6 additions & 0 deletions defs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3218,6 +3218,7 @@ typedef signed int s32;
#define UNW_4_14 (0x200)
#define FLIPPED_VM (0x400)
#define HAS_PHYSVIRT_OFFSET (0x800)
#define OVERFLOW_STACKS (0x1000)

/*
* Get kimage_voffset from /dev/crash
Expand Down Expand Up @@ -3260,6 +3261,7 @@ typedef signed int s32;

#define ARM64_STACK_SIZE (16384)
#define ARM64_IRQ_STACK_SIZE ARM64_STACK_SIZE
#define ARM64_OVERFLOW_STACK_SIZE (4096)

#define _SECTION_SIZE_BITS 30
#define _SECTION_SIZE_BITS_5_12 27
Expand Down Expand Up @@ -3332,6 +3334,9 @@ struct machine_specific {
char *irq_stackbuf;
ulong __irqentry_text_start;
ulong __irqentry_text_end;
ulong overflow_stack_size;
ulong *overflow_stacks;
char *overflow_stackbuf;
/* for exception vector code */
ulong exp_entry1_start;
ulong exp_entry1_end;
Expand Down Expand Up @@ -5770,6 +5775,7 @@ ulong cpu_map_addr(const char *type);
#define BT_CPUMASK (0x1000000000000ULL)
#define BT_SHOW_ALL_REGS (0x2000000000000ULL)
#define BT_REGS_NOT_FOUND (0x4000000000000ULL)
#define BT_OVERFLOW_STACK (0x8000000000000ULL)
#define BT_SYMBOL_OFFSET (BT_SYMBOLIC_ARGS)

#define BT_REF_HEXVAL (0x1)
Expand Down

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